At present

the automatic generation control(AGC) system for circulating fluidized bed(CFB) unit is always in the process of turbulent regulation

making the control mechanisms act frequently. The reason is that the change rules of control variables with load(namely the static characteristics) are not clear for the CFB combustion system. Therefore

taking account of the capacity and structure of the CFB boiler

the cyclone performance and the desulphurization efficiency

through regulating the particle size distribution of the feedstock

the bed pressure drop and the mass ratio of the primary air to secondary air

the optimized combustion of CFB boiler can be achieved which is featured by the optimal particle size distribution of bed material

land the carbon content in fly ash and bottom ash also can be reduced. Then

by setting up the equations of energy balance

material balance and carbon balance in the furnace

and solving the nonlinear equation groups by Newton method

the static behaviors of the CFB boiler under conditions with different loads

different coal types and different particle size distributions of feedstock were obtained. The optimal regulation amounts for control variables such as the feed coal flow

primary air flow

secondary air flow

limestone flow and bottom ash flow were ascertained and used as the set values. Thus

the decoupling control of combustion system can be realized for CFB boilers.